The present invention relates to a dual cut header assembly particularly to a sunflower header.
The optimal harvesting height of sunflowers is very depending on the height of the plant. In some fields, this height can vary from 3 m to less than 1 m. Furthermore, it is an advantage for the operator of the agricultural vehicle or the farmer to have a constant, relatively short stubble height once the agricultural vehicle has harvested the sunflower seeds. Therefore, the sunflower header is formed as a dual cut header assembly comprising a header and a chopper. The header is provided to be lifted by the agricultural vehicle to cut the top part of the crop material, or the sunflowers, from the field at a first height. The chopper is suspended from the header and provided to cut the remaining crop material at a second height which is lower than the first height. Thereby, such dual cut header assembly has the possibility to harvest the sunflowers at a height that can vary from 3 m to 1 m via the header, while, via the chopper, the assembly can cut the stems and stalks close to the ground surface so that only a short stubble remains on the field.
Using existing dual cut header assemblies, the operator has to control the height of the header, so that sunflowers, or other crop material, can be cut at an optimal height for harvesting. Thereby, typically this height is manually controlled based on visuals and experience of the operator. While controlling the height of the header, the height of the chopper also changes along with the height of the header, because the chopper is suspended from the header. Typically, the chopper is suspended from the header via at least one actuator. The operator of the agricultural vehicle also manually controls the height of the chopper to cut the stalks and stems close to the ground surface at a desired height. A disadvantage of this configuration is that controlling the two heights requires a significant concentration and experience. Particularly, the optimal heights are not constant so that the operator is constantly adjusting the two heights. As a result of this, the maximum driving speed wherein the operator is able to control these heights is limited. Increasing the driving speed would not allow the operator to optimally control both the height of the header and the height of the chopper.
Attempts have been made to hydraulically couple the height of the chopper to the height of the header via a master slave configuration with hydraulic actuators. Tests have shown that such coupling does not lead to the desired result because other factors also influence the optimal distance between the header and the chopper. One example of such factors is the flatness of the field. Also, when the agricultural vehicle carrying the sunflower header is provided with a rear lift system, so that the height of the rear wheels can be adjusted based on environmental parameters, the ideal distance between header and chopper is significantly influenced by the settings of the rear lift system. When testing this header with a hydraulic master slave coupling between header and chopper it has become clear that when the chopper height is too low, the chopper touches the ground surface and digs in to the ground surface so that, when the agricultural vehicle is driven forward over the field, a bulldozer effect is obtained eventually blocking the correct further operation of the vehicle. When the chopper is too high, the stalks and stems that remain on the field are too high and make further operations on the field difficult. Both situations are therefore highly undesired.
It is an object of the present invention to provide a dual cut header assembly wherein an optimal chopper height can be more easily achieved.